It is found in nature only in traces produced by natural neutron irradiation in uranium ores. It is produced artificially by neutron irradiation of uranium-238.

• 钸广泛用作核反应堆燃料和核子武器装料。原生性的钸仅在铀矿石中有痕量发现,由自然的中子辐射作用产生,造成这种中子辐射的是铀－238。